The instant invention relates to template guided drilling. More particularly, the invention relates to apparatus adapted for assisting of machinists in utilizing drilling templates.
Drilling templates are commonly serve dual functions of drill site location and tactile/visual assistance in drill bit selection. Where, for example, a drilling template prescribes a square four inch on center pattern of diagonally paired xe2x85x9cxe2x80x3 and xc2xdxe2x80x3 holes, such template will commonly comprise a flat aluminum sheet having holes positioned and sized identically with the holes to be drilled. Such an aluminum sheet template efficiently facilitates tactile/visual selection of the xc2xdxe2x80x3 and a xe2x85x9cxe2x80x3 drill bits needed for drilling. In selecting the drill bits, the operator of the template simply slides a candidate drill bit through one of the template holes to assure that the bit is of the proper gauge. If such bit will not slide through the hole in the template, the bit is immediately identified as too large. Conversely, if the candidate bit fails to closely fill the hole in the template, such bit is identified as being too small.
The exemplary drilling template less efficiently locates the prescribed drilling sites upon the surface to be drilled. Upon placement of such drilling template over such surface, the four drilling sites are known to be at the centers of the four holes of the template. However, the exact locations of the centers are not immediately identified. A skilled machinist may be able to closely approximate the center of each hole utilizing a scratch awl to indent the drilling sites. However, in many applications, the tolerance for inaccuracy in drill site location is beyond the marking capability of a machinist. The instant inventive kit or assemblage assists drilling template operators in performing such drilling site locating function by providing a quill and stylus scribing instrument; the instrument having a plurality of interchangeable scribing point centering guides; such guides matching common gauges of drill bits.
A primary structural component of the inventive assemblage or kit comprises a hollow bored stylus retaining quill having an open upper end, and having an open lower end. Preferably, the upper end of the annular outer surface of the stylus retaining quill is spirally threaded for threaded mounting thereover of an apertured slide stopping cap. Also preferably, the lower end of the annular inner wall of the stylus retaining quill forms an upwardly oriented coffered step or slide stopping ridge. Also preferably, a conical ball receiving aperture extends through the wall of the stylus retaining quill at its lower end. Also preferably, the annular outer surface of the stylus retaining quill is knurled for resisting slippage during manual handling.
A second primary structural component comprises a stylus having an upper driving end and a lower scribing end. The stylus is necessarily slidably mounted within the hollow bore of the stylus retaining quill. Preferably, the upper driving end of the stylus forms an annular upwardly oriented slide stopping ridge or coffered step which is engageable with the undersurface of the apertured slide stopping cap, such engagement limiting upward sliding motion of the stylus. Also preferably, at a point below said upwardly oriented slide stopping ridge, the stylus further forms a downwardly oriented slide stopping ridge or coffered step. Preferably, the lower end of the stylus extends through a helical spring whose upper end biases against said downwardly oriented slide stopping ridge, and whose lower end biases against or is mechanically linked to an upwardly oriented slide stopping ridge or coffered stop which is milled into the inner wall of the stylus retaining quill. For secure engagement of the lower end of the helical spring with said upwardly oriented slide stopping ridge, an upwardly opening spring receiving cup having an apertured floor is preferably disposed between the lower end of the helical spring and said upwardly oriented slide stopping ridge. Preferably, the annular outer surface of said cup has an annular flange which is engageable with said upwardly oriented slide stopping ridge for limiting downward sliding motion of the stylus. According to the aforedescribed configuration, the stylus extends axially through the helical spring and through the aperture within the floor of said cup.
Said helical spring normally upwardly positions the stylus within the hollow bore of the stylus retaining quill so that the upper driving end of the stylus protrudes upwardly through the apertured slide stopping cap, and so that the upwardly oriented slide stopping ridge of the stylus engages the undersurface of said cap. Preferably, the stylus is jointed at a point above its downwardly oriented slide stopping ridge; the joint allowing, upon wear or degradation of the lower scribing end of the stylus, replacement of the lower end of the stylus.
Preferably, the lower scribing end of the stylus forms a conical point for indenting drilling sites upon surfaces. Alternately and suitably, the lower scribing end of the stylus may incorporate a printing means, such as an ink or graphite marker, such means depositing drilling site locating indicia rather than indenting a surface.
The present inventive assemblage necessarily further comprises a plurality of differently sized scribing end centering guides for centering the lower end of the stylus within a template aperture. Preferably, each scribing end centering guide has an upper end adapted for interchangeable attachment to the lower end of the stylus retaining quill. Also preferably, each scribing end centering guide has a lower end closely fitted to the inside diameter of an aperture drilled by a commonly sized drill bit. As such apertures are typically circular, the lower end of each scribing end centering guide is preferably circular. Alternately and suitably, the lower ends of the scribing end centering guides may be configured as a plurality of radially arranged bearing surfaces positioned for contact with the annular wall of a circular template aperture. Ideally, each scribing end centering guide is configured as a second quill whose hollow bore forms, upon attachment to the lower end of the stylus retaining quill, a passage which is continuous with the hollow bore of the overlying quill. Such alignment of hollow bores allows the stylus to extend both through the bore of the stylus retaining quill and through the bore an attached second quill.
A preferred interchangeable attaching means for alternate selective attachments of the scribing end centering guides to the lower end of the stylus retaining quill comprises a quick disconnect coupling such as a floating ball locking slip joint wherein a ball bearing alternately engages with and disengages from an annular ball receiving channel milled within the upper ends of centering guides. Alternate suitable interchangeable attaching means include spring biased ball and detent locking slip joints, spring leaf and detent locking slip joints, ridge and channel locking slip joints, hook and channel locking slip joints, hook and ridge locking slip joints, lug and xe2x80x9cLxe2x80x9d slot locking slip joints, lug and xe2x80x9cLxe2x80x9d channel locking slip joints, frictionally attached slip joints, free sliding slip joints, and spirally threaded joints.
In use of the inventive assemblage (further referring to the exemplary four inch square drilling template described above) such template is precisely positioned and held at a desired location upon a surface to be drilled. Upon such positioning, the assemblage is operated by selecting a centering guide having an outside diameter of xe2x85x9cxe2x80x3. Said guide is then attached to the lower end of the stylus retaining quill. The lower end of said guide is then inserted into one of the xe2x85x9cxe2x80x3 apertures of the template until the lower surface of the guide rests upon the surface to be drilled. A percussive striking force is then applied to the upper driving end of the stylus, driving the lower scribing end of the stylus into the surface to be drilled, accurately forming an indentation, accurately marking one of the xe2x85x9cxe2x80x3 drilling sites. Alternately, where the lower scribing end of the stylus is configured for application of printed indicia rather than a surface indentation, pressurized contact, as opposed to percussive contact, may be applied to the upper driving end of stylus. The tool is then withdrawn and inserted into the diagonally opposed xe2x85x9cxe2x80x3 aperture of the template. There, a similar percussive striking force is applied. The tool is then withdrawn from the template, the xe2x85x9cxe2x80x3 guide is removed, and is replaced by a xc2xdxe2x80x3 centering guide. Center marking of both xc2xdxe2x80x3 apertures of the template then proceeds in a manner identical to the markings of the xe2x85x9cxe2x80x3 apertures.
Preferably, the inventive assemblage is configured as a kit containing a quill and stylus assembly, and containing groupings of second quills matching common drill bits. Kits matching numbered, alphabetically lettered, English, or metric drill bit sizes may be provided.
Accordingly, it is an object of the present inventive assemblage to provide a surface scribing stylus slidably mounted within a quill, and to further provide a plurality of differently sized interchangeable scribing end centering guides. It is a further object of the present invention to provide such an assemblage capable of efficiently and economically performing center marking within drilling templates.
Other and further objects, benefits, and advantages of the present invention will become known to those skilled in the art upon review of the Detailed Description which follows, and upon review of the appended drawings.